This invention relates generally to repairing cracks in workpieces, and more particularly, to a method for repairing cracks in structural workpieces using a cammed drawbolt approach.
Cracks occur in structural materials during manufacturing processes such as casting of metal or ceramic objects and molding of synthetic material objects. Cracks also occur during use of structural objects due to causes including stress, fatigue, aging or other conditions of use. The material of the structural object and the conditions of its use are taken into account in determining the most practical repair technique. X-ray, fluorescent penetrant or various other inspection techniques are used to evaluate the characteristics of cracks and the need and practicality for repair. Some cracks may be small enough that they represent no risk to performance, but others will require repair to allow safe and compliant operation of the machine, such as a power generator, locomotive, ship propulsion engine or other system. Many cracks may best be repaired by a technique not requiring extreme heating as occurs with, for example, welding or soldering. Extreme heat may induce stresses in the structural workpiece material which may be difficult or expensive to remedy. Bonding using chemical agents which soften a portion of a structural workpiece may be undesirable, because solvents or other softening agents may damage the material of the structural workpiece surfaces or require expensive or complex treatments to remove solvent residue. Large structural components, for example, diesel engine cast components, such as frames and engine blocks, are expensive to manufacture. Maintaining a spare engine in a user's inventory is rarely done due to the associated inventory costs, and waiting to re-engine a power generator, locomotive, ship or other industrial user may create considerable cost and inconvenience for the user. A technically sound, low-cost crack repair method is needed to facilitate reliable repair of cracks to minimize downtime and overall life cycle cost. Some materials other than metals have characteristics, such as limited temperature tolerance or corrosion, which make repair by techniques using heat or chemical bonding difficult or impossible.